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Pathophysiology of coal pneumoconiosis in equidae.

Authors

Davis-GW; Farrell-RL; Hamlin-RL; Smith-CR; Ghosh-S

Source

NIOSH 1974 Jun; :1-42

Link

NIOSHTIC No.

00180433

Abstract

A group of 12 coal mine ponies was studied to characterize the physiological parameters and pathological changes in spontaneous pneumoconiosis in Equidae. The six coal mines where the ponies worked were located in eastern West Virginia and western Pennsylvania. Ponies spent 6 to 8 hours/day, 6 days/week in the mine. In one case the ponies were housed in the mine. Ponies had worked in the mines for 5 to 20 years. Gross lesions were seen at necropsy, similar to mild simple coal workers pneumoconiosis. None of the animals demonstrated disease comparable with the more complicated human disease. Numerous punctate 1 millimeter to 1 centimeter coal macules were found in the lungs. The macules occurred primarily in subpleural and dependent portions of the lung, microscopically consisting of peribronchiolar aggregates of dust laden pulmonary macrophages. Bronchiolar mucosal hyperplasia and peribronchiolar and perivascular fibrosis were also noted along with secondary emphysema and muscular hypertrophy. Ultrastructurally retained dust particles characterized the pulmonary lesions. A proliferation of alveolar type-II cells was noted as the primary host response to the dust with an overproduction of surfactant and the formation of many aberrant lamellar bodies. A comparison was made of the animal lungs morphometrically with human lungs. Those ponies with longer exposure periods demonstrated more severe pulmonary lesions.